The increasing accuracy of external radiotherapy instruments such as intensity modulated radiotherapy, CyberKnife, and proton beam has enabled pursuit of the concept of “male lumpectomy” for prostate cancer treatment [1]. This would parallel accept breast cancer treatment regimens. A critical aspect of any radiotherapy treatment is the quality assurance (QA) that the patient is receiving the planned dose delivery. A three-dimensional phantom can be used to verify and validate the spatial energy distribution, total amount, and consistency of dosage. Typically, a phantom with a simple, uniform geometry is used. Although anthropomorphic, the phantoms described in Refs. [2] and [3] were constructed based upon a representative size and shape of a patient. Radiation detectors (e.g., ion chambers, thermoluminescent dosimeter, and radiochromic film) are built into the phantom at specific fixed locations (e.g., prostate and bladder). These locations cannot be moved within the model.
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